CN103438881B - A kind of method suppressing fiber optic loop interlude backscattering noise - Google Patents
A kind of method suppressing fiber optic loop interlude backscattering noise Download PDFInfo
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- CN103438881B CN103438881B CN201310363891.2A CN201310363891A CN103438881B CN 103438881 B CN103438881 B CN 103438881B CN 201310363891 A CN201310363891 A CN 201310363891A CN 103438881 B CN103438881 B CN 103438881B
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Abstract
The invention discloses a kind of method suppressing fiber optic loop interlude backscattering noise, utilize Y waveguide by signal amplitude value to be
input light wave be divided into signal amplitude value and be
with signal amplitude value be
two bundle output light-waves, one at Y waveguide is provided with a signal phase modulator, conditioning signal phase-modulator between tail optical fiber and fiber optic loop, the square-wave modulation signal that described signal phase modulator is produced satisfies condition:
; And:
.The present invention can reduce or eliminate the irreplaceable error (noise) that fiber optic loop interlude backscattering causes effectively, thus improves the precision of fibre optic gyroscope further.
Description
Technical field
The present invention relates to fiber-optics gyroscope field, particularly relate to a kind of method of the fiber optic loop interlude backscattering noise suppressed in fibre optic gyroscope.
Background technology
Fibre optic gyroscope has all solid state, the advantage such as movement-less part, reliability are high, response is fast, flexible structure, potential accuracy are high, measurement range is wide, long service life due to it, is widely used in each technical field.
In optical fibre gyro, fiber optic loop is formed by the optical fiber coiling of hundreds and thousands of meters, due to the imperfection of the material of optical fiber own and manufacturing process, backscattering is there is when light wave is transmitted in fiber optic loop, likely interfere between backscattering ripple or between backscattering ripple and the main ripple of signal, these interference light intensities can inevitably be added to Sagnac light intensity (Sagnac), namely on signal light intensity, this brings irreplaceable error to input, thus makes the precision of fibre optic gyroscope be subject to great impact.The appearance of wide range SLD light source and employing greatly reduce backscattering noise and other optical noises in fiber optic loop, but the noise that this method causes for the backscattering of fiber optic loop mid point coherent length (fiber optic loop interlude) cannot be eliminated.Therefore, elimination or reduction fiber optic loop interlude backscattering noise have great importance for the fibre optic gyroscope developing high level of accuracy.
Summary of the invention
For prior art above shortcomings, object of the present invention is just to provide a kind of method suppressing fiber optic loop interlude backscattering noise, can effectively reduce or eliminate the irreplaceable error (noise) that fiber optic loop interlude backscattering causes, thus improve the precision of fibre optic gyroscope further.
To achieve these goals, the technical solution used in the present invention is such: a kind of method suppressing fiber optic loop interlude backscattering noise, is characterized in that: utilize Y waveguide by signal amplitude value to be
input light wave be divided into signal amplitude value and be
with signal amplitude value be
two bundle output light-waves, two tail optical fibers of Y waveguide are connected with the two ends of fiber optic loop, thus make signal amplitude value be
with
output light-wave respectively along getting back to Y waveguide around fiber optic loop after one week clockwise and counterclockwise;
One at Y waveguide is provided with a signal phase modulator between tail optical fiber and fiber optic loop, the signal amplitude value exported from this tail optical fiber is
output light-wave through signal phase modulator carry out phase-modulation laggard enter fiber optic loop, get back to Y waveguide around fiber optic loop after one week, the signal amplitude value exported from another tail optical fiber is
output light-wave enter signal phase modulator around fiber optic loop after one week, carry out getting back to Y waveguide after phase-modulation through signal phase modulator;
Conditioning signal phase-modulator, the square-wave modulation signal that described signal phase modulator is produced satisfies condition:
；
And:
;
In formula:
for the range value of the modulation signal of t;
for the semiperiod of modulation signal;
for the transit time of fiber optic loop;
for modulation signal is at the range value of front semiperiod,
for modulation signal is at the range value in later half cycle;
with
for natural number.
Further, in order to make the sensitivity of signal maximum, the range value of the square-wave modulation signal that described signal phase modulator produces satisfies condition:
。
Compared with prior art, the invention has the advantages that: by regulating amplitude and the frequency of modulation signal, make to interfere between two clockwise and counterclockwise bundle backscattering light waves to disappear mutually, and two bundle backscattering ripples disappear mutually with two interference of restrainting the main ripple of signal, thus can effectively reduce or eliminate the irreplaceable error (noise) that fiber optic loop interlude backscattering causes, thus improve the precision of fibre optic gyroscope further.
Accompanying drawing explanation
Fig. 1 is the system chart of the method applied in the present invention.
Embodiment
Below in conjunction with drawings and Examples, the invention will be further described.
Embodiment: see Fig. 1, a kind of method suppressing fiber optic loop interlude backscattering noise, utilizes Y waveguide by signal amplitude value to be
input light wave be divided into signal amplitude value and be
with signal amplitude value be
two bundle output light-waves, two tail optical fibers of Y waveguide are connected with the two ends of fiber optic loop, thus make signal amplitude value be
with
output light-wave respectively along getting back to Y waveguide around fiber optic loop after one week clockwise and counterclockwise;
One at Y waveguide is provided with a signal phase modulator between tail optical fiber and fiber optic loop, the signal amplitude value exported from this tail optical fiber is
output light-wave through signal phase modulator carry out phase-modulation laggard enter fiber optic loop, get back to Y waveguide around fiber optic loop after one week, the signal amplitude value exported from another tail optical fiber is
output light-wave enter signal phase modulator around fiber optic loop after one week, carry out getting back to Y waveguide after phase-modulation through signal phase modulator;
Conditioning signal phase-modulator, the square-wave modulation signal that described signal phase modulator is produced satisfies condition:
；
And:
;
In formula:
for the range value of the modulation signal of t;
for the semiperiod of modulation signal;
for the transit time of fiber optic loop;
for modulation signal is at the range value of front semiperiod,
for modulation signal is at the range value in later half cycle.
This method first under signal madulation dorsad scattered noise analyze:
In optical fibre gyro, two tail optical fibers of Y waveguide and fiber optic loop welding, fiber optic loop interlude is due to the reason of the aspects such as the material of optical fiber own or manufacturing process, there is backscattering, as shown in Figure 1, the light wave now converged at Y waveguide has 4 row, can be expressed as following form:
。……（1）
In formula:
for the signal amplitude of clockwise light wave;
for the signal amplitude of counterclockwise light wave;
for the signal amplitude of Y waveguide input light wave;
for Sagnac phase shift;
for the range value of the modulation signal of t;
for the transit time of fiber optic loop;
for clockwise lightwave signal is in interlude backscatter signals amplitude;
for counterclockwise lightwave signal is in interlude backscatter signals amplitude;
for total backscatter signals amplitude.
Like this Y waveguide converge interfere produce interference light intensity signal (output signal) be:
。……（2）
In formula: <> represents and is averaged, because optical frequency is much larger than the response time of current all detectors, is therefore averaged and represents and be averaged in detector response time magnitude.
4 row light waves in formula (1) are substituted into formula (2) can obtain:
。……（3）
Be easy to get by formula (3), due to backscattering in actual fiber (
) the signal receiving (resolving Sagnac phase shift) that exists for bring interference, therefore Section 1 is signal terms, after two be noise item.
Thus the fiber optic loop interlude backscattering Noise Method that is inhibited:
Select suitable modulation signal range value and frequency, can make, below in braces and be zero, the noise because backscattering causes can be eliminated like this.
For in practical application, modulation signal generally adopts periodic signal to modulate.And optical fibre gyro actual fabrication is adopt cycle square wave modulation (abbreviation square-wave frequency modulation) with majority in production, and therefore the present invention analyzes square-wave frequency modulation.
General square-wave modulation signal can be represented with formula below:
；……………………（4）
for the semiperiod of modulation signal.
In order to eliminate backscattering noise, make signal to carry out demodulation calculation, the following condition of square-wave modulation signal demand fulfillment simultaneously:
。..........................................(5)
Namely the semiperiod of modulation signal equals the transit time of fiber optic loop, and this modulation is modulated also referred to as intrinsic.The condition that this cycle (frequency) also just limiting modulation signal will meet.
Following form can be expressed as square wave intrinsic modulation signal:
；
........................................（6）
Then be easy to get:
。…………（7）
Carry it into formula (3), and make a-b=Φ, a+b=Ψ has:
。…（8）
For the modulation of square wave intrinsic, restituted signal is:
。……………（9）
Formula (8) is brought into and is arranged:
。………（10）
Formula (10) is analyzed, known when in round bracket in Section 2 being zero, even if there is backscattering
, it also can not have an impact to signal receiving, namely can eliminate the irreplaceable error (noise) that backscattering causes.But will ensure signal to export, namely Section 1 can not be zero simultaneously.
Namely require that following formula is set up:
；………………（11）
The solution easily being solved (9) by mathematics is:
。…………………（12）
The square wave intrinsic modulation signal that satisfied (12) require all can eliminate the irreplaceable error caused by fiber optic loop interlude backscattering.
In specific implementation process, to ask sensitivity maximum, namely
maximum, then the range value of the square-wave modulation signal making above-mentioned signal phase modulator produce satisfies condition:
；........(13）
Get special circumstances,
have:
。
Finally it should be noted that, above embodiment is only in order to illustrate technical scheme of the present invention but not restriction technologies scheme, those of ordinary skill in the art is to be understood that, those are modified to technical scheme of the present invention or equivalent replacement, and do not depart from aim and the scope of the technical program, all should be encompassed in the middle of right of the present invention.
Claims (1)
1. suppress a method for fiber optic loop interlude backscattering noise, it is characterized in that: utilize Y waveguide by signal amplitude value to be
input light wave be divided into signal amplitude value and be
with signal amplitude value be
two bundle output light-waves, two tail optical fibers of Y waveguide are connected with the two ends of fiber optic loop, thus make signal amplitude value be
with
output light-wave respectively along getting back to Y waveguide around fiber optic loop after one week clockwise and counterclockwise;
One at Y waveguide is provided with a signal phase modulator between tail optical fiber and fiber optic loop, the signal amplitude value exported from this tail optical fiber is
output light-wave through signal phase modulator carry out phase-modulation laggard enter fiber optic loop, get back to Y waveguide around fiber optic loop after one week, the signal amplitude value exported from another tail optical fiber is
output light-wave enter signal phase modulator around fiber optic loop after one week, carry out getting back to Y waveguide after phase-modulation through signal phase modulator;
Conditioning signal phase-modulator, the square-wave modulation signal that described signal phase modulator is produced satisfies condition:
；
And:
;
In formula:
for the range value of the modulation signal of t;
for the semiperiod of modulation signal;
for the transit time of fiber optic loop;
with
for natural number.
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| CN103868507B (en) * | 2014-03-17 | 2016-06-08 | 北京航空航天大学 | The double; two interference type optical fiber gyroscope of difference based on tail optical fiber coupling polarizes nonreciprocal error inhibition method |
| CN111238464B (en) * | 2020-01-19 | 2021-11-09 | 浙江大学 | Detection method of resonant optical gyroscope based on reciprocity modulation and time division switching |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5898496A (en) * | 1997-02-14 | 1999-04-27 | Allied Signal Inc | Optical signal noise reduction for fiber optic gyroscopses |
| EP1780506A2 (en) * | 2005-11-01 | 2007-05-02 | Honeywell International Inc. | Interferometric fiber optic gyroscope (IFOG) using Modulation Technique for real-time calibration of wavelength reference under harsh environment |
| CN101886925A (en) * | 2010-05-27 | 2010-11-17 | 北京大学 | Multi-wavelength interference type optical fiber gyro based on carrier modulation |
| CN102506896A (en) * | 2011-10-19 | 2012-06-20 | 浙江大学 | Device and method for testing back scattering noise in resonator optical gyro (ROG) by resonant cavity technology |
-
2013
- 2013-08-20 CN CN201310363891.2A patent/CN103438881B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5898496A (en) * | 1997-02-14 | 1999-04-27 | Allied Signal Inc | Optical signal noise reduction for fiber optic gyroscopses |
| EP1780506A2 (en) * | 2005-11-01 | 2007-05-02 | Honeywell International Inc. | Interferometric fiber optic gyroscope (IFOG) using Modulation Technique for real-time calibration of wavelength reference under harsh environment |
| CN101886925A (en) * | 2010-05-27 | 2010-11-17 | 北京大学 | Multi-wavelength interference type optical fiber gyro based on carrier modulation |
| CN102506896A (en) * | 2011-10-19 | 2012-06-20 | 浙江大学 | Device and method for testing back scattering noise in resonator optical gyro (ROG) by resonant cavity technology |
Non-Patent Citations (1)
| Title |
|---|
| 干涉型光纤陀螺仪关键技术研究;杨兴光;《中国优秀硕士学位论文全文数据库信息科技辑》;20050315(第1期);正文第12-20页 * |
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